Ig Henneman (born 1945 in Haarlem) is a Dutch violist and composer regarded as a key figure in the Netherlands' free-improvisation scene. She started out as a classical violist in the ASKO Ensemble, began composing while co-leading the rock band FC Gerania, and founded her own quintet in 1985. Since 1999 she has led the long-running Duo Baars-Henneman together with saxophonist/clarinetist Ab Baars, her partner, alongside projects such as the Ig Henneman Sextet and the Queen Mab Trio. In 2021 she was knighted (Ridder in de Orde van Oranje-Nassau) for her contribution to composed and improvised music.
Ig Henneman and Ab Baars celebrated their joint birthday on 28 December 2025 with a concert in Dokzaal Amsterdam, coinciding with the 25th anniversary of their duo.
At the jubilee concert, the live CD Baars Henneman 150 @ Wels Unlimited 2025 was released.
On 1 November 2026, a follow-up concert is scheduled at Splendor Amsterdam under the title Ig Henneman 80 Ab Baars 70=150.
In September 2021, Henneman was appointed Knight in the Order of Orange-Nassau during her 75th birthday concert at Orgelpark Amsterdam.
In September 2022, she released the retrospective album Outside the Rain Has Stopped, featuring work from previous years.
